Blow-moulding of ostomy bags

ABSTRACT

An ostomy collecting bag is provided. The collecting bag has a continuous wall with a curvature instead of sealed edges. The collecting bag is truly three-dimensional. The collecting bag may be obtained by injection blow-moulding or extrusion blow-moulding. Methods of producing an ostomy collecting bags by either injection blow-moulding or extrusion blow-moulding is also provided. In injection blow-moulding, a pre-form is injection moulded and subsequently the pre-form is blow-moulded into an ostomy collecting bag. In extrusion blow-moulding, a tube is extruded and subsequently blow-moulded into an ostomy collecting bag. The ostomy collecting bag can thus be made without seals at the edges, which provides a more flexible collecting bag with a larger interior volume.

The invention relates to a collecting bag for use in an ostomy appliance(or an ostomy bag) that is blow-moulded—thus given a three-dimensionalstructure. Furthermore, the invention relates to methods of producingsuch a collecting bag.

BACKGROUND

In connection with surgery for a number of diseases in thegastro-intestinal tract, one of the consequences in many cases is thatthe patient is left with an abdominal stoma, such as a colostomy or anileostomy in the abdominal wall for the discharge of visceral contents.The discharge of visceral contents cannot be regulated at will. For thatpurpose, the user will have to rely on an appliance to collect thematerial emerging from such opening in a bag, which is later emptiedand/or discarded at a suitable time.

An ostomy appliance may be in the form of a two-piece appliancecomprising a wafer and a collecting bag which may be coupled to andun-coupled from each other through a coupling. This means that the waferdoes not need to be separated from the skin of the user as often asexchange of the collecting bag requires. The wafer only needs to bechanged every third or fourth day depending on the user, whereas thecollecting bag may be changed more than once per day.

An ostomy collecting bag typically comprises two layers of film materialthat is welded or glued along the edges of the bag.

SUMMARY OF THE INVENTION

The invention relates to a collecting bag for use in an ostomy appliancethat has a rounded shape so that the transition from the side facing theuser to the side facing away from the user follows a rounded curve, whenseen in cross-section. The collecting bag may in another or relatedaspect be obtainable by extrusion or by injection blow-moulding. In theextrusion blow-moulding process, an endless tube is initially extrudedand subsequently the tube is blow-moulded to provide the finishedcollecting bag. In the injection blow-moulding process, a pre-form isinitially injection moulded and subsequently the pre-form isblow-moulded to provide the finished collecting bag. Attachment meansmay be insert moulded in the blow-moulding process. A collecting bagaccording to the invention may be truly three-dimensional. Furthermore,the collecting bag has no sealed edges that provide reduced flexibilityof the collecting bag along the edges.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a prior art ostomy bag.

FIGS. 2 to 4 illustrate embodiments of a collecting bag according to theinvention, FIGS. 2 and 3 illustrate cross-sectional views of twoembodiments of the collecting bag and FIG. 4 illustrates a perspectiveview of the collecting bag.

FIG. 5 illustrates a mould for use to injection mould a pre-form.

FIG. 6 illustrates a mould for use in a blow-moulding process, thepre-form is indicated in dotted lines.

FIG. 7 illustrates a principle sketch of blow-moulding of an endlesstube.

FIG. 8 illustrates the mould for moulding a collecting bag.

FIG. 9 illustrates insertion of an endless tube into a mould accordingto the invention. FIG. 10 illustrates how a collecting bag according tothe invention is blow-moulded. FIGS. 11 and 12 illustrate furtherembodiments of a collecting bag according to the invention.

FIGS. 13A and 13B illustrate the collecting bag of FIG. 11 seen from thefront and the rear.

FIGS. 14A and 14B illustrate an expandable cross-section of a collectingbag.

FIGS. 15A and 15B illustrate an extrusion blow-moulded collecting bagwith flex-zones. FIG. 15A illustrates a cross-section of the mould andthe bag, and FIG. 15B illustrates a front view of the finished bag.

FIG. 16 illustrates how a wafer can be insert moulded to the collectingbag during the blow-moulding process.

DETAILED DESCRIPTION OF THE INVENTION

In a first aspect, the invention relates to a collecting bag for use inan ostomy appliance, where the collecting bag comprises a generallycontinuous foil material defining a continuous wall of the collectingbag, with a front of the wall facing away from the user and a rear ofthe wall facing the user, where the transition between the front of thewall and the rear of the wall is smooth and defines a rounded curvature.

By generally continuous foil is meant that the collecting bag isprovided in one piece of foil material so that the collecting bag has nosealed edges. By a smooth transition is meant that there are no sharpedges in the transition between the front of the wall and the rear ofthe wall—rather the transition from the front to the rear of the wall isnot well-defined and the transition is a rounded curvature. This meansthat the cross-section defines a smooth curve in a sectional view of thecollecting bag.

In a second aspect, the invention relates to a collecting bag for use inan ostomy appliance wherein the collecting bag is obtained by injectionblow-moulding.

In a third aspect, the invention relates to a collecting bag for use inan ostomy appliance that is obtained by extrusion blow-moulding.

Ostomy bags (or collecting bags for use in ostomy appliances) aretypically made by joining two or more films into a collecting bag, thusthese prior art bags typically have well-defined front and rear walls.The joining in these prior art bags are typically made by either weldingor gluing. A collecting bag according to the first, second and/or thirdaspect of the invention has no joined edges and is therefore moreflexible than a prior art bag. Furthermore, such a collecting bag isable to benefit from the full volume of the collecting bag since theoutput can be stored at all positions inside the bag and is not limitedby joined edges that may provide un-fillable volumes of the collectingbag. For thick output, the un-fillable volume of a collecting bag may beas large as 5% or 10% of the volume of the bag. Finally, there is norisk of leaking through joined edges in collecting bag according to thefirst, second or third aspect of the invention.

In other words, an ostomy collecting bag with joined edges has to have alarger surface area to provide the same interior collecting volume as anostomy collecting bag having no joined edges. It is an advantage for theuser to provide an ostomy collecting bag having as small a surface aspossible, so as to make the collecting bag as inconspicuous as possible.

The sealed edges alone provide an increase in the surface of up to 5 mmaround the entire periphery of the bag. For a generally oval bag that isabout 200 mm long and about 100 mm wide the increase in surface areacaused by the sealed edges may amount to between 10% and 15%.

Moreover a collecting bag having no sealed edges (without a well-definedfront wall and rear wall) will be less likely to be subject topancaking—that is, the situation where the front wall and the rear wallof the ostomy bag cling to each other. Pancaking is a well-know problemfor ostomy appliances and may in extreme situations lead to problems ofstoring the output in the collecting bag. A collecting bag according tothe first, second or third aspect, will naturally assume a position inwhich the front of the wall and the rear of the wall have a distancebetween them. This distance will minimise the risk of pancaking.

The collecting bag according to the first aspect may be obtained byeither injection blow-moulding or extrusion blow-moulding. This meansthat the first aspect may be combined with the second aspect or thethird aspect of the invention.

In a fourth aspect, the invention relates to a method of producing acollecting bag for use in an ostomy appliance comprising the steps of

-   -   a) Injection moulding a pre-form    -   b) Inserting the pre-form into a blow-moulding machine    -   c) Blow-moulding the collecting bag

In a fifth aspect, the invention relates to a method of producing acollecting bag for use in an ostomy appliance comprising the steps of

-   -   a) Extruding a tube    -   b) Inserting the tube into a blow-moulding machine    -   c) Blow-moulding the collecting bag

Collecting bags for ostomy appliances are typically made by joining twoor more films into a collecting bag. When the collecting has been weldedor glued the remaining part sticking out from the edges arecut-off—which leads to waste.

Injection moulding a pre-form and subsequently blow-moulding thecollecting bag is an easy process to control because a standard pre-formcan be used for a variety of bags and then the finish of the bag can becontrolled by the mould used in the blow-moulding process.

Extrusion blow-moulding is a fast and easy process that can runcontinuously.

The process of extrusion blow-moulding is well-known and includesmelting and extruding the material into a hollow tube (sometimes calleda parison) and then subsequently inserting the hollow tube into a cavityof a mould. The melting may be provided by heating the material to e.g.approximately 140° C. or 160° C. depending on the material.

In the following, whenever referring to proximal side of a device orpart of a device, the referral is to the skin-facing side, when theostomy collecting bag is worn by a user. Likewise, whenever referring tothe distal side of a device or part of a device, the referral is to theside facing away from the skin, when the ostomy collecting bag is wornby a user. In other words, the proximal side is the side closest to theuser, when the collecting bag is fitted on a user and the distal side isthe opposite side—the side furthest away from the user in use.

The axial direction is defined as the direction of the stoma, when theostomy collecting bag is worn by a user. Thus, the axial direction issubstantially perpendicular to the abdominal surface of the user.

The radial direction is defined as transverse to the axial directionthat is transversely to the direction of the stoma.

A collecting bag for use in an ostomy appliance is well-known in theart. In the following, whenever referral is made to a collecting bag, acollecting bag suitable for use in an ostomy appliance is meant. Such acollecting bag may also be referred to as an ostomy collecting bag.

The collecting bag may be made of gas- and liquid impermeablefoil-material (for example of polyethylene (PE), polyvinyl-dichloride(PVdC), polyvinyl-chloride (PVC) or ethylene-vinyl-acetate (EVA)),polyurethane (PU) or other polymers that could be used in thermo plasticforming process. For the type of collecting bag that is subject of thisinvention, the material could be a two-component foil including forexample PVdC or a Thermoplastic elastomer or other barrier-layer as theinnermost layer and a poly-olefin layer as the outermost. Examples ofpoly-olefin could be PE, Poly-propylene (PP) or EVA. It is also possibleto make a multi layer combination of polymers such as for example acombination of PU, PVdC and EVA to obtain other properties of theextruded polymer. Other examples of materials could be a compoundedmaterial made of PE, PP or EVA.

A prior art collecting bag that is welded or glued around the edges,comprises a front wall facing away from the user (on the distal side ofthe bag) and a rear wall facing the user (on the proximal side of thebag). Likewise, when used, a collecting bag according to this inventioncomprises a proximal side facing the user and a distal side facing awayfrom the user. The waste inlet opening is provided in the collecting bagin the proximal side and placed in the upper part of the collecting bagso that when a user stands up, the waste inlet opening will be above themidline of the collecting bag. This leaves a larger collecting volumebelow the waste inlet opening. Thus, the top of the collecting bag isdefined as the part closest to the waste inlet opening, and the bottomis defined as the opposite part. The length direction of the collectingbag is defined as the direction from top to bottom of the ostomycollecting bag.

When the collecting bag forms part of an ostomy appliance, thecollecting bag may be provided with a waste-inlet opening and theappliance will be provided with attachment means for connecting thecollecting bag either directly to the user or to a wafer.

In the extrusion blow-moulding process, the waste inlet opening may beprovided by providing the collecting bag with a connector flange duringthe moulding process and then subsequently cutting this flange off.

In the injection blow-moulding process, the waste inlet opening mayalready be present in the pre-form.

The attachment means for the collecting bag may be in form of a waferdirectly attached to the collecting bag and adapted for directlyadhering to the abdominal surface of a user and surrounding the stoma.This provides for a so-called one-piece ostomy appliance.

The attachment means may also be in form of coupling means adapted forreleasably coupling to matching coupling means positioned at a waferwhich in turn may be adhered to the abdominal surface of a user. Thisprovides for a so-called two-piece ostomy appliance.

The collecting bag according to the first, second and/or third aspect ofthe invention may be made as a truly three-dimensional collecting bag sothat it also has a dimension larger than the combined thickness of thefront and the rear of the wall of the bag in the axial direction. Inother words, the collecting bag will have a surface area that is largerthan the cross-sectional area. A conventional collecting bag will, whenempty, only have the dimension corresponding to the sum of the thicknessof the front wall and the thickness of the rear wall in the axialdirection—and furthermore, the surface area of a conventional collectingbag corresponds to the cross-sectional area.

A three-dimensional collecting bag may provide a larger collectingvolume at the lower portion of the collecting bag—towards the bottom ofthe bag.

The collecting bag according to the invention may have a rounded shapelike a balloon. However, the collecting bag may also assume a moreelongated shape that is curved or rounded off towards the bottom.

In an embodiment of the invention, the thickness of the wall of thecollecting bag is between 50 μm and 200 μm or between 50 μm and 100 μm.The thickness of the wall may be approximately 75 μm. This thicknessprovides for a good balance between the barrier properties and theflexibility that is needed in the collecting bag for use in an ostomyappliance.

In an embodiment of the invention, the collecting bag is soft andflexible.

By soft and flexible is meant that the collecting bag has a reducedrigidity compared to other types of collecting bags that are notsuitable for use in an ostomy appliance.

For example, collecting bags for use in an ostomy appliance may have atensional modulus of between 50 N/mm² and 500 N/mm². The tensionalmodulus may be measured according to the guidelines given in DIN 53457.Thus in an embodiment of the invention, the wall of the collecting baghas a tensional modulus of between 50 N/mm² and 500 N/mm². In a relatedembodiment, the wall of the collecting bag has a tensional modulus ofbetween 100 N/mm² and 150 N/mm². The wall of the collecting bag may havea tensional modulus of approximately 120 N/mm².

The flexibility of the finished collecting bag depends on the tensionalmodulus and the thickness of the wall. Thus in an example, the tensionalmodulus of the wall of the collecting bag is between 100 N/mm² and 150N/mm², e.g. approximately 120 N/mm² and the thickness of the wall isbetween 50 μm and 100 μm, e.g. approximately 75 μm. This provides for asoft and flexible collecting bag for use in an ostomy appliance.

In an embodiment, the collecting bag is designed so that it provides abetter fit to the body of the user.

For example, the collecting bag may have a curvature in the lengthdirection so that bottom portion is positioned closer to the body, whenthe bag is worn. This is an advantage if the stoma sits on a top pointof a users abdomen e.g. if the user has a bulgy stomach.

One way of doing this is to provide a variation in the rigidity over thewall of the collecting bag so that the front of the wall of the bag(facing away from the user) is more rigid than the rear of the wall ofthe bag (facing the user). By more rigid is meant that the front of thewall has a tensional modulus that is at least 10% higher than the rearof the wall of the bag. This will have the effect that the rear of thewall of the bag will extend more easily when the bag is filled—and thusthe output from the stoma will have a tendency to store itself in thevolume of the bag towards the user.

In another embodiment, the collecting bag has a curvature in the lengthdirection so that the bottom portion is positioned away from the body,when the bag is worn. This construction is advantageous if the user hasa rather flat abdomen—or if the stoma is sitting in a recess of theusers abdomen. In this case the user does not have to carry the output(or the bag) against the surface of the body. This embodiment can beachieved by providing a collecting bag where the rear of the bag is morerigid than the front of the bag.

The variation in rigidity of the wall of the collecting bag can be doneby providing a net-structure or a ribbed structure in the surface of theblow-moulding mould. The denseness of the net/ribbed structure willcontrol the rigidity of the wall of the collecting bag so that densernet/ribs will provide a more rigid finished wall-structure. Another wayof varying the rigidity of the wall of the ostomy bag is to vary thethickness of the wall of the collecting bag.

In the injection blow-moulding process, this may be done by varying thethickness of the pre-form so that one part of the pre-form is thickerthan another part. For example, the part that will become the front ofthe collecting bag can be thicker than the part that will become therear of the collecting bag—or vice versa. Furthermore, the variation inrigidity can be done by using a two-component-moulding process in thepre-form so that one part of the pre-form is provided by one type ofmaterial and the other is provided of a more rigid type of material.

In the extrusion blow-moulding process, this may be done by varying thethickness of the tube so that one part of the tube is thicker thananother part. For example, the part that will become the front of thecollecting bag can be thicker than the part that will become the rear ofthe collecting bag—or vice versa.

In an embodiment, the collecting bag is provided with a ribbed structureobtained by blow-moulding the bag in a mould that is provided with ribs,thereby obtaining a bag that is expandable when filled.

When injection blow-moulding is used, the pre-form may be provided withribs.

In an embodiment, the ribs may be provided as alternating ribs andgrooves extending transversely across the collecting bag. This willprovide a bag that is expandable in the length direction. In anotherembodiment the ribs may be provided as alternating ribs and groovesextending longitudinally along the collecting bag. This will provide abag that is expandable in the width direction. Typically 15-25 ribs areprovided. The depth of the ribs may be between 0.3 mm and 0.7 mm, forexample approximately 0.5 mm.

In an embodiment of the invention, at least part of the collecting bagis provided with flex-zones. Providing a collecting bag with flex-zonesresults in a collecting bag that is more flexible and has improvedcharacteristics for adaptation to the body. Flex-zones can be obtainedby providing the blow-moulding mould with a curvature on the innersurface of the mould. Three to four flex-zones extending across the bagare preferable. The flex-zones may have a depth of between 1 mm and 2mm.

In an embodiment, the pre-form is approximately 3-4 cm long andapproximately 1 mm thick. The length is defined as the distance from theattachment means to the end farthest away from the attachment means. Apre-form of this size will be able to be blown up to a finishedcollecting bag that is approximately 50-200 μm, e.g. 75 μm, thick andhaving a size suitable for collecting output from a stoma, for example180 mm×140 mm.

In an embodiment, the pre-form is approximately 1 cm long and has athickness of 1.5 mm. Such a pre-form will also be able to be blown up inthe blow-moulding process to provide a finished collecting bag of forexample 180 mm×140 mm. In another embodiment, the pre-form isapproximately 15 cm long and has a thickness of about 0.5 mm. Such apre-form will also be able to be blown up in the blow-moulding processto provide a regular sized finished collecting bag for use in an ostomyappliance of for example 180 mm×140 mm.

In an embodiment, the pre-form may be smaller, for example approximately1 cm long and approximately 1 mm thick. This provides a small finishedcollecting bag for use in an ostomy appliance that is generally circularand has a diameter of approximately 100 mm.

In an embodiment, one part of the pre-form has a thickness ofapproximately 0.75 mm and in another part of the pre-form the thicknessis approximately 1.25 mm. This will provide a collecting bag having apart being more rigid than the other. The pre-form may also be providedwith several parts of a thickness of e.g. approximately 0.75 mm andseveral other parts of a thickness of e.g. approximately 1.25 mm. Thisprovides a collecting bag that is more expandable in some parts than inothers, i.e. the collecting bag may be more stretchable in some partsthan in others.

In an embodiment, the pre-form comprises two different types ofmaterial. For example one type of material may be more rigid thananother type of material. Different types of material in the pre-formwill lead to a finished collecting bag having variation in the materialproperties, for example variation in flexibility and stretchability. Asan example, two different types of PE may be used, one having atensional modulus of 140 N/mm² for the front of the wall and anothertype of PE having a tensional modulus of 100 N/mm² for the rear of thewall.

The tube (or parison) that is used in the extrusion blow-moulding may beapproximately 1 mm thick and have an outer diameter of approximately 30mm. A tube of this size will be able to be blown up to a finishedcollecting bag that is approximately 50-200 μm, e.g. 100 μm, thick and(depending on the size of the cavity in the mould) having a sizesuitable for collecting output from a stoma, for example 180 mm×140 mm.This thickness of the finished collecting bag provides a collecting bagthat functions properly in use and is generally soft and flexible andthus suitable for use in an ostomy appliance.

Parts that need to be very precise in the collecting bag may beinjection moulded. This includes for example the attachment means. Theattachment means, meaning the adhesive base plate, in case of aone-piece ostomy appliance, or the coupling, in case of a two-pieceostomy appliance, may be insert moulded either in the injection mouldingprocess, in case a pre-form is injection moulded, or directly in theblow-moulding process. Insert moulding is done by inserting a finishedpart into the mould and then injection mould the pre-form or blow-mouldthe collecting bag at the finished part.

For example, in the blow-moulding process, the attachment means may bepositioned in the mould close to the opening into the collecting bag.The cavity of the mould may include a side section to provide room forthe attachment means and for leading foil material to the side section.The connection between the attachment means and the collecting bag willoccur as a result of the central inner part of the attachment meansmelting together with the moulded foil material that later constitutesthe collecting bag.

In the injection moulding, the connection will occur as a result of thetop part of the attachment means melting together with the flange of thepre-form—thus when the pre-form is ready to be put into theblow-moulding mould, it already includes attachment means.

In both processes, the process of welding attachment means to thecollecting bag is eliminated.

If the collecting bag is to be provided with a filter, the filter may beinsert moulded in the pre-form.

In an embodiment, a cover layer may be inlayed in the blow-mouldingmould prior to blow-moulding the collecting bag. In this case the coverlayer—e.g. in form of a so-called comfort layer made of non-woven ortextile—is already attached to the collecting bag when it exits theblow-moulding process.

EXAMPLES Extrusion Blow-Moulding Example

A suitable material, e.g. a blend of PE an EVA is extruded in anextruder at 130° C. The extruded blend of PE and EVA is formed as a tubein a ring die and the tube goes into the two part blow mould. The tubecould have a thickness of 1 mm, but it could be as low as 0.1 mm and asthick as 4 mm. In this example, the bag is a so called two-piece ostomyappliance. The coupling is, in this case, a part of the bag, and thedimensions and the design of the coupling is integrated in the mould.

When the tube is in the mould, it is blown up to the desired shape.Depending of the design of the mould, the tube will be blown up to abag, with a preferred thickness between 0.1 and 0.4 mm. The thickness ofthe finished bag could, however, be as thin as 0.01 mm and as thick as1.5 mm depending of the choice of extruded polymer and the design of thebag. Also the process in combination with the design of the mould andthe temperature distribution in the mould will make it possible to getbags with differentiated thickness of material.

The blowing time is dependent of the thickness and the raw materials,but with a material temperature of 130° C. and an air valve that applies6 bar pressure, the bag can be blown up to finished shape in less than 1second. Higher temperature can reduce the time, and the blowing part ofthe process can be done in less than 0.1 second, if the conditions areright. It is also possible to expand the blowing time to a much longertime, e.g. 10 sec. if needed.

The result is a seamless collecting bag for use in an ostomy appliancewith less waste compared to the traditional way of making ostomycollecting bags

Injection Blow-Moulding Example

First a pre-form is injection moulded. This can be done in a standardinjection moulding process. The pre-form could e.g. be made of a blendof PE and EVA or PE, EVA and PVdC or other suitable thermoplasticpolymers. The pre-form could be 3 cm long with a diameter of 2 cm andwith a thickness 1 mm. The dimensions of the pre-form depend of thematerials and the design of the finished bag. The open end of thepre-form could be made with the dimension of a coupling for a two-pieceostomy system. The injection moulding process can make very precisedimensions, hence elements with narrow tolerances can with advantage befinalized in the injection moulded pre-form prior to the blowingprocess.

After the pre-form has been injection moulded, it is placed in a blowmould form, heated up, and blown into the desired shape and design. AnEVA/PE blend could be heated up to 130° C. and then blown up. Theblowing time could be approx. 1 sec. but could be as low as 0.1 sec. andas long as 10 sec. if desired. The thickness of the finalized bag willpreferable be approx. 0.1 mm, but could also be as low as 0.01 mm and upto 1.5 mm

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a prior art collecting bag 100 and FIG. 2 illustratesa collecting bag 1 according to the invention. The collecting bag 1 ismade by injection moulding a pre-form (see FIG. 5) and then subsequentlyblow-moulding the finished ostomy bag (see FIG. 6).

A prior art collecting bag 100 as shown in FIG. 1 has a top 101 and abottom 102 and is made of a front wall 103 and a rear wall 104 of filmmaterial and then subsequently sealed (typically welded) along theperiphery as indicated at 105. The prior art collecting bag is alsoprovided with a stoma receiving opening 106. Thus, the prior artcollecting bag is two-dimensional (flat) prior to use.

FIG. 2 illustrates a collecting bag according to the invention 1. Thisbag also has a top 2 and a bottom 3 and a stoma receiving opening 4.However, this bag does not comprise any seals—e.g. welds—along theperiphery and can therefore be made in a three-dimensional structure asshown in FIG. 2. In other words, the bag is made of one film 5 that maydefine a front 6 and a rear 7. Thus, when the bag is to be filled, itwill already have a three-dimensional structure and the tendency of thesheets to cling to each other will be minimised. Furthermore, problemswith the hard and un-flexible seal are eliminated.

The flange 8 illustrated in FIG. 2 can be used to attach to attachmentmeans—e.g. by welding or alternatively by insert moulding the attachmentmeans directly to the bag.

FIG. 3 also illustrates a collecting bag 1 according to the invention.The same reference numbers are used to indicate the same features. Thisbag is similar to the bag of FIG. 2, the only difference being that thebag of FIG. 3 is obtained by extrusion blow-moulding by extrusionmoulding an endless tube (see FIG. 7) and then subsequently blow-mouldthe finished collecting bag (see FIG. 8).

The collecting bag 1 in FIG. 3 comprises a connector flange 8′. Thisconnector flange 8′ can be used to be cut off to define the waste inletopening into the bag. Then it is possible to later on attach attachmentmeans to the collecting bag—e.g. by welding or adhering. Alternativeattachment means can be directly attached to the collecting bag byinsert moulding—see FIG. 16.

FIG. 4 illustrates a perspective view of a one-piece ostomy appliancecomprising a collecting bag 1 as the one in FIG. 2 or FIG. 3. The ostomyappliance comprises a wafer 9 for adhering the collecting bag to a user.The collecting bag 1 has a rounded shape as indicated in the figure.

FIG. 5 illustrates a mould 10 that may be used to mould a pre-form 11 byinjection moulding. The pre-form 11 may subsequently be used to form theostomy collecting bag.

The dimensions of the pre-form may be a tubular element that isapproximately 12 mm in outer diameter and 10 mm in inner diameter and 30mm long, where the length is indicated as d in FIG. 5. This provides atubular element of approximately 1 mm in cross-section, which whensubjected to blow-moulding will be approximately 100 μm thick. Thefinished ostomy collecting bag will have a size correspondingapproximately to a MIDI bag that is 180 mm×140 mm.

FIG. 6 illustrates a mould 20 that may be used to mould the finishedcollecting bag 21. A pre-form 11, obtained by injection moulding, isinserted into the mould 20 and subsequently blown up to provide thefinished collecting bag 21.

FIG. 7 illustrates a principle sketch of parts of a blow-mouldingmachine that may be used in the invention. The machine comprises a mould30 with an inner cavity 31. In the sketch the mould consists of twomould halves 30 a and 30 b. The material is fed into the machine by anextruder 32 that feeds the molten material into a tube or parison 12.The machine also includes a blow-pin 33 to blow the material intocontact with the inner surface of the cavity 31. Furthermore, themachine in the sketch includes a plunger or core 34 that keeps thesidewall of the tube 12 to a controlled thickness.

FIG. 8 illustrates a collecting bag 1 according to the invention in theclosed mould 30. The division between the mould halves 30 a and 30 bappears from the figure. Furthermore, in the mould, a side section 31 aof the inner cavity defines a connector flange 8′ for the collectingbag—allowing the finished bag to be provided with a waste inlet opening.

FIG. 9 illustrates how an endless extruded tube 12 is inserted into theopen mould 30. The tube may be approximately 30 mm in outer diameter andmay have a thickness of approximately 1 mm in cross-section. When alength of this tube has been subjected to blow-moulding, it will beapproximately 100 μm thick. The finished collecting bag will have a sizecorresponding approximately to a MIDI bag that is 180 mm×140 mm.

FIG. 10 illustrates moulding of the finished collecting bag 1. Thelength of the tube is blow-moulded inside the mould 30 to provide thefinished collecting bag 1. FIG. 10 also illustrates how the next part ofthe tube 12 is ready to be inserted into the mould 30 to provide thenext finished collecting bag.

FIGS. 11 and 12 illustrate two embodiments 40, 50 of ostomy bagsaccording to the invention. In the ostomy bag 40 illustrated in FIG. 11,the front 46 of the ostomy bag is more rigid than the rear 47 of the bagso that the output will have a tendency to store itself towards the rear47 of the bag. This has the effect that the output will be stored closeto the body and the ostomy bag will not bulge out from the front of theuser. In the ostomy bag 50 illustrated in FIG. 12, the front 56 of theostomy bag is less rigid than the rear 57 of the bag so that the outputwill have a tendency to store itself towards the front 56 of the bag.This has the effect that the bag will not be in close contact with thebody, when it is filled.

FIGS. 13A and 13B illustrate an ostomy bag 40 as shown in FIG. 11 seenfrom the front (FIG. 13A) and rear (FIG. 13B) respectively. The front 46of the bag is more rigid than the rear 47. The difference in rigidity isin this case obtained by providing a net-structure having a densestructure 49 on the front and a more open structure 49′ at the rear.

FIGS. 14A and 14B illustrate how a ribbed cross-section 60 of an ostomybag can be used to provide an expandable bag. In FIG. 14A thecross-section 60 is shown in a non-extended configuration and in FIG.14B the same cross-section is shown when it has been extended.

FIGS. 15A and 15B illustrate an extrusion blow-moulded collecting bag 70with flex zones 71. The flex-zones 71 can be obtained by providing themould 30′ (FIG. 15A) with a curvature 35 corresponding to the flex-zones71 on the finished bag.

FIG. 16 illustrates how attachment means 80 can be insert moulded to thecollecting bag during the blow-moulding process. The mould 30 is fed bya tube 12 as described above. To provide the general outline of thecollecting bag, the mould comprises two mould halves 30 a and 30 b toprovide the cavity 31 for the collecting bag. The mould 30 is providedwith a side section cavity 31 a for providing the connector flange thatin this case can be used for attaching the attachment means 80 bymelting the molten foil material to the attachment means. The attachmentmeans is inserted into the mould between mould half 30 b and anadditional mould part 30 c so that the attachment means 80 are kept inposition during the moulding process.

1. A collecting bag for use in an ostomy appliance, where the collecting bag comprises a generally continuous foil material defining a continuous wall of the collecting bag, with a front of the wall facing away from the user and a rear of the wall facing the user, where the transition between the front of the wall and the rear of the wall is smooth and defines a rounded curvature.
 2. A collecting bag for use in an ostomy appliance wherein the collecting bag is obtained by injection blow-moulding.
 3. A collecting bag for use in an ostomy appliance that is obtained by extrusion blow-moulding.
 4. The collecting bag as claimed in claim 1 that is obtained by injection blow-moulding.
 5. The collecting bag as claimed in claim 1 that is obtained by extrusion blow-moulding.
 6. The collecting bag as claimed in any of the preceding claims, wherein the collecting bag is provided with a waste inlet opening.
 7. The collecting bag as claimed in any of the preceding claims, wherein the thickness of the wall of the collecting bag is between 50 μm and 200 μm.
 8. The collecting bag as claimed in any of the preceding claims, wherein the collecting bag is soft and flexible.
 9. The collecting bag as claimed in any of the preceding claims, wherein the wall of the collecting bag has a tensional modulus of between 50 N/mm² and 500 N/mm ², preferably between 100 N/mm² and 150 N/mm².
 10. The collecting bag as claimed in any of the preceding claims, wherein the collecting bag is designed so that it provides a better fit to the body of the user.
 11. The collecting bag as claimed in any of the preceding claims, comprising a variation in the rigidity over the wall of the collecting bag.
 12. The collecting bag as claimed in claim 11, wherein the front of the wall of the bag is more rigid than the rear of the wall of the bag.
 13. The collecting bag as claimed in any of the preceding claims, wherein the thickness of the wall of the collecting bag varies.
 14. The collecting bag as claimed in any of the preceding claims, wherein the collecting bag is provided with a ribbed structure.
 15. The collecting bag according to claim 14, wherein the bag that is expandable when filled.
 16. The collecting bag according to claim 14 or 15, wherein the ribs are provided as alternating ribs and grooves extending transversely across the collecting bag.
 17. The collecting bag according to claim 14 or 15, wherein the ribs are provided as alternating ribs and grooves extending longitudinally along the collecting bag.
 18. The collecting bag as claimed in any of the preceding claims, wherein at least part of the collecting bag is provided with flex-zones.
 19. An ostomy appliance comprising a collecting bag according to any of the preceding claims and a wafer attachable to a user.
 20. A one-piece ostomy appliance comprising a collecting bag as claimed in any of claims 1 to 19 and attachment means in form of a wafer directly attached to the collecting bag and adapted for directly adhering to the abdominal surface of a user.
 21. A two-piece ostomy appliance comprising a collecting bag as claimed in any of claims 1 to 19 and attachment means in form of coupling means adapted for releasably coupling to matching coupling means positioned at a wafer that in turn may be adhered to the abdominal surface of a user.
 22. A method of producing an ostomy collecting bag comprising the steps of a). Injection moulding a pre-form b). Inserting the pre-form into a blow-moulding machine c). Blow-moulding the ostomy collecting bag
 23. The method according to claim 22, further including inserting a filter into the mould prior to injection moulding the pre-form.
 24. The method according to any of claim 22 or 23, wherein the blow-moulding mould is provided with a net-structure or a ribbed structure in the surface of the blow-moulding mould.
 25. The method according to any of claims 22 to 24, further including inserting attachment means into the mould prior to injection moulding the pre-form.
 26. The method according to any of claims 22 to 25, wherein a cover layer is inlayed in the blow-moulding mould prior to blow-moulding the collecting bag.
 27. The method according to any of claims 22 to 26, wherein the pre-form is moulded in a two-component moulding so that one part of the pre-form is provided by one type of material and the other is provided of another type of material.
 28. A method of producing a collecting bag for use in an ostomy appliance comprising the steps of a). Extruding an endless tube b). Inserting a length of the tube into a blow-moulding machine c). Blow-moulding the collecting bag in a blow-moulding mould
 29. The method according to claim 28, wherein the blow-moulding mould is provided with a net-structure or a ribbed structure in the surface of the blow-moulding mould.
 30. The method according to any of claim 28 or 29, further includes inserting attachment means into the mould prior to blow-moulding the collecting bag.
 31. The method according to any of claims 28 to 30, wherein a cover layer is inlayed in the blow-moulding mould prior to blow-moulding the collecting bag. 